In the Linux kernel, the following vulnerability has been resolved:
mptcp: ensure context reset on disconnect()
After the blamed commit below, if the MPC subflow is already in TCP_CLOSE
status or has fallback to TCP at mptcp_disconnect() time,
mptcp_do_fastclose() skips setting the send_fastclose flag and the later
__mptcp_close_ssk() does not reset anymore the related subflow context.
Any later connection will be created with both the request_mptcp flag
and the msk-level fallback status off (it is unconditionally cleared at
MPTCP disconnect time), leading to a warning in subflow_data_ready():
WARNING: CPU: 26 PID: 8996 at net/mptcp/subflow.c:1519 subflow_data_ready (net/mptcp/subflow.c:1519 (discriminator 13))
Modules linked in:
CPU: 26 UID: 0 PID: 8996 Comm: syz.22.39 Not tainted 6.18.0-rc7-05427-g11fc074f6c36 #1 PREEMPT(voluntary)
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
RIP: 0010:subflow_data_ready (net/mptcp/subflow.c:1519 (discriminator 13))
Code: 90 0f 0b 90 90 e9 04 fe ff ff e8 b7 1e f5 fe 89 ee bf 07 00 00 00 e8 db 19 f5 fe 83 fd 07 0f 84 35 ff ff ff e8 9d 1e f5 fe 90 <0f> 0b 90 e9 27 ff ff ff e8 8f 1e f5 fe 4c 89 e7 48 89 de e8 14 09
RSP: 0018:ffffc9002646fb30 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88813b218000 RCX: ffffffff825c8435
RDX: ffff8881300b3580 RSI: ffffffff825c8443 RDI: 0000000000000005
RBP: 000000000000000b R08: ffffffff825c8435 R09: 000000000000000b
R10: 0000000000000005 R11: 0000000000000007 R12: ffff888131ac0000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS: 00007f88330af6c0(0000) GS:ffff888a93dd2000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f88330aefe8 CR3: 000000010ff59000 CR4: 0000000000350ef0
Call Trace:
tcp_data_ready (net/ipv4/tcp_input.c:5356)
tcp_data_queue (net/ipv4/tcp_input.c:5445)
tcp_rcv_state_process (net/ipv4/tcp_input.c:7165)
tcp_v4_do_rcv (net/ipv4/tcp_ipv4.c:1955)
__release_sock (include/net/sock.h:1158 (discriminator 6) net/core/sock.c:3180 (discriminator 6))
release_sock (net/core/sock.c:3737)
mptcp_sendmsg (net/mptcp/protocol.c:1763 net/mptcp/protocol.c:1857)
inet_sendmsg (net/ipv4/af_inet.c:853 (discriminator 7))
__sys_sendto (net/socket.c:727 (discriminator 15) net/socket.c:742 (discriminator 15) net/socket.c:2244 (discriminator 15))
__x64_sys_sendto (net/socket.c:2247)
do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1))
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
RIP: 0033:0x7f883326702d
Address the issue setting an explicit fastclosing flag at fastclose
time, and checking such flag after mptcp_do_fastclose().
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (5.5): severity, escalated by confirmed exploitation. This CVE's 5.5 is its impact severity (EG Severity), not escalated.
- EG Severity
- 5.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.1% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-24). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines.
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it